Examples of such analyzing devices are blood gas analyzers, which are, for example, provided as portable analyzers for determining POC (Point Of Care) parameters, for example blood gases (O2, CO2, pH), electrolytes (e.g., K+, Na+, Ca++, Cl−), metabolites (e.g., glucose and lactate), hematocrit, hemoglobin parameters (e.g., tHb, SO2, etc.) and bilirubin, and which are mainly used for decentralized and quick determination of the above parameters in whole blood samples. Examples of such analyzers are the cobas b 123 and cobas b 221 systems from Roche Diagnostics. Analogous uses in veterinary medicine and the use of serum, plasma, urine and dialysate samples are also common.
In some cases, such analyzers are especially made for only one type of sample container, so that the device-side input facility only allows sample input by means of, for example, a syringe or a capillary tube.
Common sample containers that are used for transporting samples from a sample collection site to an analyzer and the device-side sample input facility thereof are, especially for blood samples:                Syringes: Syringes, in particular specifically adapted blood gas analysis syringes, available in the market may be made of plastic or glass, and can differ in their filling volume (approx. 1 ml to 20 ml) and the anticoagulant used. The conical parts of syringes, where the needles are connected for taking blood samples, are standardized by the Luer standard (DIN-EN20594-1; EN1707; EN20594-1). In addition, the minimum inner diameter of a Luer taper is defined by the standard for sterile hypodermic syringes for single use (EN ISO 7886-1). Due to the large filling volume, one syringe often provides enough sample for several measurements.        Capillary tubes: Capillary tubes, especially those for blood gas analyses, available in the market may be made of plastic or glass, and again can differ in their filling volume and the anticoagulant used. However, the filling volume of capillary tubes is significantly less than that of syringes (approx. 50 μL to 250 μL) and thus provides for only one analysis per sample container. Furthermore, the outside diameter of capillary tubes that may be used depends on the filling volume and the analyzer employed.        
In conventional analyzing devices, the device-side sample input may be divided into two main groups:                Filling mouth: A filling mouth is usually made of a soft plastic material, where, depending on the analyzer used, capillary tubes and/or syringes may be connected. Depending on the analyzer and mode of operation used, different input methods are possible:                    Aspiration: is possible from capillary tubes (e.g., with the cobas b 123 from Roche Diagnostics). The capillary tube is attached to the filling mouth. Then, the sample is automatically aspirated by the analyzer.            Injection: is possible with syringes (e.g., with the cobas b 221 from Roche Diagnostics). The syringe is pressed against the filling mouth. Then, the sample is actively injected by the user.                        Aspiration needle: Some blood gas analyzers, such as the cobas b 221 and the cobas b 123, are equipped with a retractable needle (steel tube) alone or in combination with a filling mouth. The tube is inserted into an opening of the sample container, for example a syringe. Depending on the analyzer used, insertion of the tube is either executed manually or automatically by the analyzer. Then, the analyzer aspirates the sample via the tube.        
The following table provides an overview of the sample input examples by means of selected blood gas analyzers. In the table, “Yes” means that the sample input type stated is possible with the respective analyzer.
TABLE 1Examples of sample input by means of selected blood gas analyzersFilling mouthAspirationfromAspirationAspirationcapillaryfromInjectiontube forAnalyzertubesyringewith syringesyringecobas b 121/OMNI CYesNo*NoYescobas b 221/OMNI SYesNo*YesYescobas b 123YesNo*NoYesOPTI ® CCAYesNo*NoNo*Note:Yes, with additional adaptor - for OPTI ® CCA, such an adaptor is available.
Coagulate traps or “clot catchers” can be used to prevent blood clots and tissue particles from entering the analyzer. Clot catchers help prevent blockages in the device or false measurement results due to blood clots by means of integrated retention elements, for example an integrated mechanical grid. Alternatively, appropriate filter or sieve structures as well as other retention elements known to the skilled person may be used as retention devices.
Such a clot catcher may, for example, be used in an analyzer that is equipped with a filling mouth and operated in the aspiration mode using capillary tubes as sample containers, wherein the clot catcher is placed between the capillary tube and the filling mouth.
In other embodiments, a clot catcher may, for example, be used in an analyzer that is equipped with a filling mouth and operated in the injection mode using syringes as sample containers, wherein the clot catcher is placed between the syringe and the filling mouth.
In analyzers equipped with sample input devices working via aspiration needles, usually no clot catcher is used.
The clot catcher available from Roche Diagnostics is, without limitation, suitable for all measurements with capillary tubes and Roche Microsampler® containers. However, in combination with syringes, the clot catcher is typically only suitable for devices and operation modes where the user can actively inject the sample. This clot catcher is made of a thermoplastic elastomer (TPE).
When using this known clot catcher, it is firmly slid onto the sample container filled with blood (e.g., a capillary tube, a Roche Microsampler® container, or a syringe). Then, an analysis is conducted according to the respective instruction manuals.
A disadvantage of all clot catchers known from the state of the art is that with analyzers, the design or the mode of operation of which allows aspiration of a sample only up to a certain point; they do not allow the use of syringes as sample containers.